Go into the quadruped position (on hands and knees) with shoulders stacked over hands and hips over knees. Put one hand behind the head and bring the elbow down to the hand on the ground. That elbow should remain straight throughout the movement. Then rotate the opposite way, bringing your elbow towards the sky as high as you can. Make sure your eyes are following the elbow moving. Breathe in through the nose as you go down. Breathe out through the mouth as you go up. These movements should be slow and controlled.